Distributed dynamic state estimator enables seamless DSA

Abstract

This paper/panel proposes an integrated and seamless infrastructure for protection, control and operation of an electric power system that enables a seamless Dynamic Security Assessment. At the lower level of the infrastructure a dynamic state estimation of protection zones (individual components) operates continuously for the purpose of providing protection for the zone. This scheme simplifies the protection approach for the zone by not requiring coordination with other protection zones. The scheme provides the real time dynamic model of the zone as well as the real time operating conditions. The scheme is ideally fitted in the most recent automation schemes for substations based on merging units and process bus with GPS synchronization — in this case the implementation is as simple as connecting a computing device (PC or relay) to the process bus. An object oriented approach has been implemented which provides the dynamic state and model estimate of each protection zone (individual component) in a standard syntax and format. The component dynamic state and model estimate is referenced to UTC time. At the substation, synthesis of all components of the same UTC time stamp provides the substation state estimate. This task is performed each cycle (60 times per second for 60 Hz systems and 50 times per second for 50 Hz systems) and the substation state estimate is transmitted to the control center. At the control center synthesis of all substation state estimates of the same UTC time stamp provides the system wide state estimate (system wide real time model). This approach provides the real time model of the system at speeds of 60 times per second and latency in the order of one cycle. The paper describes the use of the real time model for dynamic security assessment in a seamless way. The DSA can be performed with the system wide real time model or for problems that tend to be local in nature, as the voltage/VAR control problem tends to be, the described infrastructure can provide the model of a subsystem (system of interest) and an equivalent of the rest of the system at the boundaries of the subsystem. Examples will be provided.